What The HT3B Does
The HT3B is a high-capacity exhaust-driven turbocharger sitting off the manifold on the 855-family big-cam engine. Exhaust gas spins the turbine wheel, the shaft drives the compressor wheel, and intake air gets packed into the cylinders. Lose that and you lose boost, torque, and fuel economy all at once. The driver usually notices the pull before the gauge does.
This aftermarket unit uses cast turbine and compressor housings machined to the factory mounting flanges, so it lines up on the manifold and the charge pipe without adapters. The turbine wheel is high-nickel to survive sustained exhaust gas temperature, and the rotating assembly is dynamically balanced so it spools without vibration.
Failures on these are usually predictable. Oil starvation or a plugged drain line cooks the bearings. A cracked or leaking exhaust manifold gasket bleeds off drive energy. Debris from an upstream failure chews the compressor wheel. And once shaft play opens up, the seals go and you get oil in the charge pipe.
Why These Numbers Cross
3522865 is the headline number, but the same HT3B assembly carried several numbers across its production life and across the brands that catalogued it. Holset built the turbo, Cummins listed it under its own service numbers, and BorgWarner carried it after acquiring the Holset line. Same casting, same flange pattern, same rotating group — different paperwork.
Under Cummins/Holset you will see 3801615, 3801599, 3522866, 3523272, and 3523415. BorgWarner/Holset shows 196441. Holset alone lists 4033326. These are supersessions, service-kit numbers, and remanufactured-unit numbers for the same base turbocharger, which is why a search on any one of them lands you here.
All of those numbers are listed for identification only. We are not affiliated with, endorsed by, or authorized by any OEM. Use the cross-reference as a starting point, then confirm against the tag on the unit you are pulling off.
Check Before You Order
Get your engine serial number and read the number stamped on the old turbo's compressor housing tag. The 855 family ran a long time in a lot of configurations, and cross-reference alone does not confirm fit — the engine serial or the number off the failed part does. If the tag is unreadable, measure the mounting flange and compare the oil feed and drain fittings.
Before the new turbo goes on, find out what killed the old one. Check the oil feed line for restriction, clear the drain line, inspect the air filter and charge piping for debris, and pressure-check the intercooler if fitted. Dropping a replacement onto an unresolved oil supply problem gets you a second failure in short order.
3522865 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 3522865. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| BorgWarner/Holset | 196441 |
| Cummins/Holset | 3801615, 3801599, 3522866, 3523272, 3523415 |
| Holset | 4033326 |
Frequently asked questions
Is 3801615 the same turbo as 3522865?
They cross to the same HT3B assembly in our catalog. 3801615 is one of the Cummins/Holset numbers carried for this turbocharger alongside 3801599, 3522866, 3523272, and 3523415. Cross-reference is a starting point only — verify against your engine serial number or the tag on the unit you are replacing.
Will this fit my NTC855 if the old turbo tag is gone?
Go by the engine serial number instead. This unit is built for Cummins NTA855 and NTC855 big-cam 14L engines, but the 855 family ran in many configurations and we cannot promise fitment from a description alone. Pull the serial off the block and confirm before ordering.
What causes an HT3B to fail early after replacement?
Almost always oil supply or debris. A restricted feed line or plugged drain line starves and cooks the bearings, and any leftover debris in the charge piping from the previous failure will hit the compressor wheel. Clear the lines, inspect the piping, and check the air filter before you install the replacement.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.